AM is generally a process in which three-dimensional (3D) objects are constructed utilizing a computer model of the objects. These processes are used in various fields, such as design related fields for purposes of visualization, demonstration and mechanical prototyping.
Various techniques of AM exist, one such technique, otherwise known as 3D printing, being performed by a layer by layer inkjet deposition of building materials. Depending on the building materials, the layers are then cured or solidified. The building materials may include modeling materials and support materials, which form the object and the temporary support constructions supporting the object as it is being built. In cases where objects include overhanging features or shapes, e.g. curved geometries, negative angles, voids, and so on, objects are typically constructed using adjacent support constructions, which are used during the printing and then subsequently removed in order to reveal the final shape of the fabricated object.
During the AM process, at least one material (“object material” or “modeling material”) is deposited to produce the desired object and at least one other material (“support material”) to provide support for specific areas of the object during building and assure adequate vertical placement of subsequent object layers. Both materials, modeling material and support material might be initially liquid and are subsequently hardened to form the required layer shape. The hardening process may be performed by a variety of methods, such as UV curing, phase change, crystallization, drying, etc. In all cases, the support material is deposited in proximity of the object layers and often forms complex geometries and fills object voids.
In such cases, the removal of the support structure is difficult and time consuming, and may damage the formed object.
Examples of materials used as support materials are soluble materials and phase change materials.
Soluble support materials are especially appropriate for supporting small parts, because large masses of soluble material may require long period of time for dissolving.
To diminish such problems, the fabricated object is often immersed in water or in a solvent that is capable of dissolving the support materials. In many cases, however, the cleaning process may involve toxic materials, manual labor and special equipment requiring trained personnel, protective clothing and expensive waste disposal. In addition, the dissolving process is usually limited by diffusion kinetics and may require very long periods of time, especially when the support constructions are large and bulky.
Other examples of support material presently used in some AM techniques are phase change materials. These, at an appropriately high temperature, melt and thus permit support removal in the liquid state. One of the drawbacks of the phase change is that the temperature required for melting the support material tends to cause deformation of the model structure.
Another example of an application that requires materials that can be easily removed is investment casting. In investment casting these materials are used for mold preparation and then removed, usually by melting, evaporation or burning in order to allow casting of another material, for example a metal.
In addition, in biomedical applications it would be beneficial to be able to produce temporary objects which are destructible or degradable, for use, for example, as temporary implants or drug delivery devices.
It would therefore be advantageous to have a material and process for AM manufacturing enabling easy, inexpensive, fast and convenient formation of self destructible objects.